New inventory of the diversity and seasonal abundance of Tephritid fruit fly species on mango orchards in Senegal

Abstract

In Senegal, the development of integrated appoaches for controlling Tephritidae fruit flies is limited by a lack of information regarding the diversity of species involved and their spatial and temporal distribution. In fact, the current related knowledges are outdated and need to be renewed, 15 years after the introduction of Bactrocera dorsalis, in the country, the most devasting mango pest. We’ve systematically monitored fruit fly populations weekly from November 2017 to October 2018. Sites were 45 orchards spread across the country's three agro-ecological mango areas. Traps Mcphail were used with four (4) sex attractants namely Eugenol methyl (ME), Terpenyl acetate (TA), Cuelure (CUE) and trimedlure (TM). DDVP (2, 2-dichlorovinyl-phosphate) insecticide was combined with lures. After 52 weeks of trapping, 10 species were caught: B. dorsalis, C. silvestrii, C. cosyra, Z. cucurbitae, C. capitata, C. ditissima, C. fasciventris, D. longistilus, C. punctata and C. bremii. B. dorsalis made up 99% of overall fruit flies caught, followed by C. syslvestrii (78%), C. cosyra (9%), Z. curcurbitae (8%) and C. capitata (2%). In Casamance B. dorsalis made up 92% of caught fruit flies and 74% in the Centre. In Niayes area, 65% of caught fruit flies were by B. dorsalis and 24% by C. sylvestrii. Through these recordings, C. silvestrii populations were surprisesingly found to becoming more dominant over those of C. cosyra, which had ever been the second major mango pest of this area, after B. dorsalis. We analyzed fruit fly abundance over the two sensitive phenology stages of mango (growing/development and maturity), across the three zones. In Niayes, B. dorsalis, C. cosyra and C. capitata were the prevalent species during the fruit growing and development stage and maturity stage. In the Centre zone, C. cosyra was the sole existing species during fruiting stages while B. dorsalis and C. cosyra occurred during maturity stage. In Casamance, B. dorsalis, C. capitata, C. cosyra and Z. cucurbitae species reached their highest population levels during the fruiting and maturity stages. Due to comparative bio-ecological and behavioural advantages of species, more knowledge is still required, to better understand their dispersal patterns. It can assist the growers in predicting population growth and taking precautionary measures.